As you consider the many topics and perspectives that make up psychology, rangingfrom a narrow focus on minute biochemical influences on behavior to a broad focus on social behaviors, you might find yourself thinking that the discipline lacks cohesion. However, the field is more unified than a first glimpse might suggest. For one thing, no matter what topical area a psychologist specializes in, he or she will rely primarily on one of the five major perspectives. For example, a developmental psychologist who specializes in the study of children can make use of the cognitive perspective or the psychodynamic perspective or any of the other major perspectives. Psychologists also agree on what the key issues of the field are . Although there are major arguments regarding how best to address and resolve the key issues, psychology is a unified science because psychologists of all perspectives agree that the issues must be addressed if the field is going to advance. As you contemplate these key issues, try not to think of them in either/or terms. Instead, consider the opposing viewpoints on each issue as the opposite ends of a continuum, with the positions of individual psychologists typically falling somewhere between the two ends. Nature (heredity) versus nurture (environment) is one of the major issues that psychologists address. How much of people’s behavior is due to their genetically determined nature (heredity), and how much is due to nurture, the influences of the physical and social environment in which a child is raised? Furthermore, what is the
interplay between heredity and environment? These questions have deep philosophical and historical roots, and they are involved in many topics
A psychologist’s take on this issue depends partly on which major perspective he
or she subscribes to. For example, developmental psychologists, whose focus is on how people grow and change throughout the course of their lives, may be most interested in learning more about hereditary influences if they follow a neuroscience perspective.
In contrast, developmental psychologists who are proponents of the behavioral perspective would be more likely to focus on environment (Rutter, 2002, 2006).
However, every psychologist would agree that neither nature nor nurture alone is
the sole determinant of behavior; rather, it is a combination of the two. In a sense, then, the real controversy involves how much of our behavior is caused by heredity and how much is caused by environmental influences.
A second major question addressed by psychologists concerns conscious versus
unconscious causes of behavior. How much of our behavior is produced by forces of which we are fully aware, and how much is due to unconscious activity—mental processes that are not accessible to the conscious mind? This question represents one of the great controversies in the field of psychology. For example, clinical psychologists adopting a psychodynamic perspective argue that psychological disorders are brought
about by unconscious factors, whereas psychologists employing the cognitive perspective suggest that psychological disorders largely are the result of faulty thinking
processes. The next issue is observable behavior versus internal mental processes. Should psychology concentrate solely on behavior that can be seen by outside observers, or should it focus on unseen thinking processes? Some psychologists, especially those relying on the behavioral perspective, contend that the only legitimate source of information for psychologists
is behavior that can be observed directly. Other psychologists, building on
the cognitive perspective, argue that because what goes on inside a person’s mind is critical to understanding behavior, we must concern ourselves with mental processes. Free will versus determinism is another key issue. How much of our behavior is a matter of free will (choices made freely by an individual), and how much is subject to determinism, the notion that behavior is largely produced by factors beyond people’s willful control? An issue long debated by philosophers, the free-will/determinism argument is also central to the field of psychology (Dennett, 2003; Cary, 2007).
For example, some psychologists who specialize in psychological disorders argue that people make intentional choices and that those who display so-called abnormal
behavior should be considered responsible for their actions. Other psychologists disagree and contend that such individuals are the victims of forces beyond their control.
The position psychologists take on this issue has important implications for the way they treat psychological disorders, especially in deciding whether treatment should be forced on people who don’t want it.
The last of the key issues concerns individual differences versus universal principles. How much of our behavior is a consequence of our unique and special qualities, and how much reflects the culture and society in which we live? How much of our behavior is universally human? Psychologists who rely on the neuroscience perspective tend to look for universal principles of behavior, such as how the nervous system operates
or the way certain hormones automatically prime us for sexual activity. Such psychologists concentrate on the similarities in our behavioral destinies despite vast differences in our upbringing. In contrast, psychologists who employ the humanistic perspective focus more on the uniqueness of every individual. They consider every person’s behavior a reflection of distinct and special individual qualities. The question of the degree to which psychologists can identify universal principles that apply to all people has taken on new significance in light of the tremendous demographic changes now occurring in the United States and around the world.